The present invention relates to an arrangement for improving a telephone system in which a plurality of analogue phones are connected to a single line.
Such parallelly coupled telephones, or party phones, can usually be found in most residences. However, the present invention is applicable to any number or group of telephones which are connected in parallel.
1. Technical Background
When there are multiple analogue phones connected to a single line there is often the problem that an in progress conversation or modem connection will be interrupted by a second user attempting to make an outgoing call.
There has been contemplated some form of centralized PBX or similar in order to resolve this problem, but this will entail an arrangement which will be too expensive for the usual customers.
2. Objects of the Invention
A main object of the present invention is to provide an arrangement which by inexpensive and yet efficient means can resolve the above problem of interruption of on-going conversation or modem connection.
Another object of the present invention is to provide an arrangement which can either be built into new phones at a very low cost or be built into an in-line adapter with a short cable for an existing phone.
Another object of the present invention is to provide an arrangement which requires a no external power for its operation.
Still another objective of the present invention is to provide an arrangement that does not require a xe2x80x9crewiringxe2x80x9d of the existing telephone installation, such as a current sensing alternative would require.
The above objects are achieved in an arrangement as stated in the preamble, which according to the present invention is characterized in that said arrangement comprises voltage sensing means, said voltage sensing means being adapted to sense a first higher DC voltage across the line in standby mode, as well as a second lower DC voltage in the active (conversation) mode.
In other words, the present invention is providing a solution based on voltage transition sensing and such a voltage sensing circuit may be inserted across the telephone itself or in the line connecting the telephone to the wall contact. When any handset in the house is lifted, the voltage is reduced at all the phones, such that each visibility devise or display at each phone location will show that the line is in the active state.
Further features and advantages of the present invention will appear from the following description taken in conjunction with the enclosed drawing, as well as from the enclosed patent claims.